If the braided stainless steel hoses you're using have rubber inside them, then they're not what is commonly used for brake systems.
Most brake line construction consists of a teflon tube reinforced by a stainless braid. The Teflon is inert and doesn't really degrade with time or exposure to chemicals, but it doesn't have the mechanical properties to handle the pressures associated with brake systems, hence the stainless braid. There are variants on this of course, with some hose assemblies having a PVC jacket over the stainless braid to prevent dirt from working its way through the braid and then eroding the Teflon tube over time. Other hoses, like those manufactured by Crown Performance, add a Kevlar braid and rubber isolation barrier between the Teflon tube and the stainless braid, which makes the hoses less compliant (less expansion under pressure), but also increases their diameter slightly and reduces the minimum bend radius.
Modern rubber hoses have some a long way with respect to how little compliance they have when new, but tend to degrade more quickly over time and with use and should be replaced every 5-7 years if you believe the manufacturers. That said, most will probably last well over 20 years under normal year round driving conditions, but the compliance becomes greater as the hose degrades and the corresponding brake performance can become degraded along with it.
Tobin
